1. Field of the Invention
The invention relates to a flipflop, particularly a D-type flipflop, having two complementary outputs, particularly for radio frequency applications.
2. Description of the Related Art
D-type flipflops have a data input to which a data signal is applied which is transferred using a clock edge of a clock signal applied to a clock input. They also frequently have two mutually complementary data outputs, a noninverting data output and an inverting data output. After a determined period of time, the noninverting data output produces the data item transferred from the data input. The inverting data output produces the inverted data item.
Conventional D-type flipflops are of two part design, comprising the master latch and the slave latch. Both latches have feedback loops which form a holding element in which a data item can be stored. While the data item at the data input is transferred to the master latch at a first clock level, a second, subsequent clock level prompts the data item to be transferred to the slave latch from the master latch and stored therein in the same way. A signal which is output from the slave latch's feedback loop is used as output signal which is applied to one of the data outputs, the signal which is complementary thereto being produced by inversion from the output signal using an inverter circuit.
Both output signals are thus generated from the same internal signal within the slave latch, with a path length which differs by an inverter being obtained for the output signal. The output signal generated using the additional inverter requires an increased propagation time, which means that the complementary output signals are applied with a time offset, as a result of which the maximum clock frequency at which the D-type flipflop can be operated is limited by the slowest output signal.
Particularly in the case of D-type flipflops having a reset function, the total propagation time is greater on account of the gates used in the slave latch.
It is an object of the present invention to provide a D-type flipflop for radio frequency applications in which the output signals are produced by the complementary outputs in a very short time and essentially simultaneously.
This object is achieved by the flipflop in accordance with patent claim 1. Other advantageous refinements of the invention are specified in the dependent claims.